This is a guest article by Assaf Levy-Be'eri, co-founder at JOYA Team, an optical technologies house offering development services for optical systems with an expertise in AR and VR.
The Augmented Reality (AR) systems field has recently expanded to many different applications and markets. With all the buzz around Metaverse, there is an understanding that AR systems will become the bridge between the real world and the virtual world and will allow the user to combine these worlds.
However, the road to a sustainable, affordable AR system that is user-friendly and that provides real-life experience is still a long one.
In order to provide a high-end user experience, the AR Eco-System develops various optical and display technologies. One of the most commonly used and most convenient to implement within the AR system is the OLED display technology.
OLED technology is still limited in the level of brightness and lifetime, hence it is not suitable for all the use cases. Several companies and research institutes around the world have been working for years to develop and improve OLED microdisplays for various AR applications. Recent publications show continuous improvements in luminance and lifetime that may result in wider use and more use cases.
In China, there is a growing activity in this field with several technologically advanced companies (e.g. Seeya, Int-OLED, etc.) that develop micro-OLEDs of various technologies and achieve excellent performances in terms of brightness, lifetime and power consumption. The Chinese central and local governments support this industry and invest billions in promoting it.
So, we believe that OLED technology is in the lead in the oncoming years for the use of many AR systems and it will take at least a few years for other technologies to tackle it and claim a leading role to enable a sustainable AR system.
As Augmented Reality systems developers, we wanted to share our insights and tips for other developers who are using OLED displays for AR:
- The first and most important rule always to consider lifetime with luminance level of OLED. There is a direct relationship between the OLED brightness and lifetime, where high luminance accelerates the rate of lifetime decline. The developer must not rely solely on the OLED luminance according to the SPEC but must examine what this means in terms of lifetime, to ensure that the luminance offered by the manufacturer is maintained for the length of lifetime planned for the OLED in the final product.
- The OLED angular distribution is wide (almost Lambertian). On other hand, a typical AR optical system uses only a limited angular cone from the display source. This means that some of the light is not being used and is being wasted. Worse than that, this light travels within the optical system and may create stray light and ghost images originating in undesired paths and reflections within the system. The optical designer must be aware of this issue and take it into account when designing the system.
- The OLED spectrum is relatively broad and requires a chromatic aberration correction in some of the optical systems. In addition, for holographic and diffractive optical systems, using an OLED is inefficient and a large portion of spectrum is wasted or produces internal stray light and causes contrast reduction. In those kinds of systems, a Laser-based display source is recommended.
- Price: OLED display price varies and can range from tens of dollars to thousands of dollars for a single panel. The price is influenced by the manufacturing technologies and materials used but the biggest factor is the display size, which directly impacts the number of panels that can be produced from a single wafer. The smaller the panel size, the more panels can be produced from a single wafer that goes through all the production processes and the price drops down accordingly. An accurate trade-off between the panel size, the resolution and the complexity of the optical system can create an optimal working point, eventually enabling to achieve a cost-effective system.
- OLED lifetime is mostly affected by temperature, where high temperature accelerates decline of OLED lifetime. Therefore, it is important to dissipate the internal heat from the OLED and to allow its conduction to the outer surfaces. In addition, it is not recommended to place other hot components near the OLED.
About the Author:
Assaf Levy-Be’eri is a physicist and optical engineer with expertise in non-imaging design and micro-displays technologies for Augmented Reality systems. He is also a Co-founder of JOYA Team - an Optical Technologies House offering optical systems’ development services with expertise in AR and VR optical systems.
JOYA Team designs optical systems using our unique development methodology that creates an optimal working point, incorporating a holistic approach, including imaging & non-imaging design, up-to-date electro-optics and display technologies, in combination with testability, manufacturability, cost and other system aspects.